Improvement in variable cut-off apparatus



stort Getint;

Letters Patent No. 109,137, dated November 8. 1870.

. n 'i l A, IMPROVEMENT IN VARIABLE CUT-OFF APPARATUS.

TBE Schedule referred to in these Letters Patent and making part of the samev To all whom it may con-cern i Be it known that I, "lnoorxs MAY, ot' Brooklyn, in thecount-y of Kings and State of New York, have invented a new and improved Gut-OIT; and vI do hereby declare the following to be a full, clear, and exact description thereof, which will enable those skilled in the art to make and use the same, reterence' being had to the accompanying drawing forming part of this specification, in which drawing- Figure 1 represents a longitudinal section ot this invention. i

Figure 2 is au inverted plan of the valve.

Figure 3 is a plan or top view of the .valve-seat.

Similar letters indicate corresponding parts.

This invention consists in the arrangement ot' an auxiliary cylinder and piston in the back of or connected to the slide-valve, in combination with suitable steam and exhaust-ports in thc valve-seat, in sueh a manner that, when the main piston has completed the required part ot' its stroke, steam is admitted to one part of the auxiliary cylinder-'and exhausted from the other part, and the auxiliary piston is caused to mov-c and to close the steam-port. in the slide-valve,

thus cutting oli'the steam at the required point ot' the l stroke. v

'llie exhaust-ports in thevalve-seal, which communicate with the exhaust-ports ot the auxiliary cylinder, are provided with slides, so that they can be adjusted, and that the time when the steam exhausts from said -auxiliary cylinder, and consequently the point ol' cutoli", can be regulated at pleasure.

,ln the drawing- 'lhc letter A designates ,the slide-valve, which is seated 011 the bottom l ot` the stema-chest, in the ordinary manner.

This bottoni or Avalve-scat is provided with two` steam-ports, a a', which connnunicate with the opposite ends ofthe main cylinder, and with two exhaustports, b 11, which communicate with'the exhaust-pipe.

The slide-valve is provided with two ports, a* a't, which control the induction ot' steam through the ports a a', and with two cavities, if* bt, which control the eduction of the steam from the main cylinder, as will be presently explained.

rlhe ports o* a'* in the slide-valve communicate with auxiliary cylinders, G U', l'orm'ed in the back ol' said slide-valve, and iitted with auxiliary pistons, l) 1)', which are connected by a rod, E.

The auxiliary cylinders are open on their outer and closed at their inner ends, and they are provided with ports, c c', through which steam is altcricly admitted and exhausted, the mouths oi' said port-s being so situated that, when the slide-valve moves on its s jat,

1 they are alternately brought over the auxiliaryportsd d', and then over the cavities e c' in the valve-seat. i

' lhe auxiliary exhaust-ports d d' are provlded with minished, and the time when the steam from the auxiliary cylinders is allowed to exhaust can be regulated;

When the slide-valve is moving in the direction of the arrow shown thereon, in iig. lot' the drawing, steam passes in through the open end of the auxiliary cylinder C, and through the ports a* and a into the main cylinder, and the main piston moves in the same direction as the slide-valve. But, by the time the main piston has completed halt` its stroke, -t-hc slide-valve has reached the position shown in fig-1, and at this point the steam from the auxiliary cylinder C exhausts through the ports c' and d', while the auxiliary cylinder U receives steam `through the cavity c and port c,

the opposite end ot' their stroke from that which they occupy in iig. Il. Lhe porta* is thereby closed, and steam is eut oil` l'rom thel corresponding end of lthe main cylinder, while the port a'f* in the valve is opened. .lhis port, however, is not in position to admit steam to ,the'maiu cylinder; but while. the main piston completes its stroke, the slide-valve is moved in the direction opposite the arrow marked thereon, in iig. 1, and bythe time the main pistou has reached the end ofits strok'e, the port a' in the valve-stat begins to open so as to admit steam to the main cylinder, while the steam from the opposite cud oi' said cylinder exhausts through gins its return stroke and when it has completed onehal t ofit-s stroke the steam is again cut oit' by the motion ot' the auxiliary pistons, as above stated.

.ln the loregoing description the time for cutting ofi' the steam has been assumed to bc at halt-stroke', 4but this time can be changed by changing the time forexhausting the steam from the auxiliary cylinders. This change is .eli'eeted by the action ot' thc slideslff'. It' these slides are pushed in, thc slide-valve has to travel a greater distance before the steam from the auxiliary cylinders allowed to exhaust, and steam is cut cti from the main piston ata later period of the stroke of its piston, and, by drawing the slides ff' out, thereverse takes place, and steam is c ut oii' at au earlier part of the stroke..

lhe slides f ll can he adjusted by hand, o r they may be connected to the governor so that they are adjusted zultomatically, as may he required.

It must he remarked that the pistons D D' might he connected to the slide-valve and thc auxiliary cylindcrs made movable without changing the result.

The auxiliary cylinders are provided with cavities,

slides, fj", whereby their area can be increasedor diand the auxiliary pistons '1) D' are suddenly moved to the iorta cavit '11* and iortb. The main )iston hel s .i 7 l l h h', to receive projections ii', on the auxiliary pissubstantially in the manner described, so that' the anxiliary piston or pistons are caused to move automatically at the proper intervals, and that, by-their motion, steam'is cui'I off from the -main cylinder at the required part ofthe stroke of the main piston.

'2. rlheA combination of slides ff with the auxiliary exhaust-ports (Z ll', substantially as described, so that; the time when the motion of the auxiliary pistons takes place can be regulated and the cut-oli` varied to any desired part of the stroke.

THOMAS MAY..

Witnesses i Y W. HAUFF,

O. WAHLERS. 

